Paris Plages. Every year from mid-July to mid-August, a stretch of the bank along the Seine is transformed into a beach. They bring in sand and palm trees and everything. This event's title is plural (Plages) because there are actually two areas set up like this: one along la Seine and another along le Bassin de la Villette. However, the one that most people go to is along la Seine. I don't know how or why this event originally started, and with no place to swim it's certainly not very convincing to me as a "beach". But it's something fun and positive for people to do outside, and I can support that.
la Tour Bistro, a model of la Tour Eiffel made out of 324 red "bistro chairs". It was constructed to honor 125 years of the Eiffel Tower's existence. Apparently a little ways from the river bank you can also watch open-air films and enjoy performances from the FNAC concert series that's associated with Paris Plages.
This is only the information that I was able to gather from my own observations and maps that were displayed along the route. It's possible that there's a lot more going on as part of this event. Honestly I just went down there to check it out and say that I'd been; I had no intention of hanging out or doing anything there. So I walked along the "beach" from one end to the other and back, and then left. Despite the rain and humidity there was still quite a crowd, and folks seemed to be enjoying themselves and in good spirits. After having visited I have to say that Paris Plages isn't really my thing, but I would recommend going at least once.
Bread and Butter [Paris] photos - JULY
Bread and Butter [Paris] photos - JUNE
Bread and Butter [Paris] photos - MAY